A big hole in the asphalt cover on the Tartu-bound side of the Kurna-Luige section of the Tallinn ring road caused the part of the road to be closed when it appeared on July 11. It now turns out major deposits of concrete waste were left inside the relatively new road section.

Postimees wrote in July how the Road Administration closed a lane on the recently completed Luige-Kurna section as sinking of the construction caused a major hole in the asphalt cover.

The agency announced yesterday that surveys have revealed the fault falls under warranty because the contractor had left concrete waste in the road section.

The Kurna-Luige road section, completed in the second half of 2014, was built by Lemminkäinen Eesti AS, and the company is still responsible for warranty, the administration reported.

The public was initially told the fault would not fall under warranty conditions. The media wrote about a major karstic fissure on the highway.

The Road Administration ordered a thorough survey from the Technical Center of Estonian Roads and declared a public procurement the winner of which would be charged with determining the causes of the sinking and propose solutions for restoration of the road surface.

Winner Nordecon carried out a thorough survey and removed the section's pavement construction. The investigation found two contributing factors: Lemminkäinen Eesti AS had used large scale concrete waste for temporary structures in the embankment that should have been removed.

The company had been required to do so by owner supervision executor Taalri Varahaldus AS that failed to verify whether the order had been carried out. Spaces in between concrete waste structures allowed sand materials to shift as a result of vibration, resulting in the pavement collapsing. Concrete waste was also discovered where pavement had not collapsed but where the thickness of the embankment was already nonexistent.

The embankment and pavement had also sunk evenly due to the former's weight in which regard the Road Administration decided to have the pavement construction restored to its initial height.

Section to open to traffic in late October

The administration required Lemminkäinen Eesti AS to perform its contract and demanded the company fix the pavement construction in October as part of warranty.

Lemminkäinen Eesti AS has previously found other factors could have been at fault for the collapse but has not presented the agency with proof of additional factors so far.

Because removing concrete waste from so deep and filling in the road could damage the part of the road open to traffic, Lemminkäinen Eesti AS has proposed a new technical solution to restore the embankment. The Road Administration has approved the project.

Lemminkäinen Eesti AS has presented the agency with a work schedule, according to which the Tartu-bound side of the Kurna-Luige section will be opened in late October. It is possible the top layer of asphalt concrete will be laid in spring should weather conditions complicate construction work.

Contractor gives difficult conditions as reason

CEO of Lemminkäinen Eesti AS Tarmo Trei said that construction conditions were very difficult on the Kurna-Luige section in 2013-2014: peat ground, deep pits, and high water level.

That is why the company constructed a temporary access road out of large debris material that remained in use for months to allow heavy trucks to move filling materials.

«Building these kinds of large rubble access roads is a common technical solution in difficult conditions like these,» Trei said.

He added that the road was dismantled once access was no longer needed, while difficult conditions probably meant not all the rubble could be removed.

«Lemminkäinen Eesti AS was prepared to cooperate with the Road Administration to determine the causes of the sinking and carry out necessary repairs immediately after the fault was discovered on the Kurna-Luige section,» Trei maintained.

He added that by now the company has put together the best possible technical solution for repair work that the administration has basically approved.